Which of the following is evidence that matter is too small to be seen without magnification? A Feeling the heat come off the flames of a fire
B Feeling the grains of salt in between your fingers
C Watching salt disappear when it dissolves in water
D Watching rain fall from the sky during a thunderstorm

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.